Fig. 3

Phenotype of spiel ohne grenzen (spg) mutants during somitogenesis. (A,B) Expression of pax[zf-b] (arrow) in the region of the midbrain and presumptive midbrain-hindbrain boundary region and pax6 (anterior to pax[zf-b] stripe) in the forebrain of wildtype (A) and spg^m216 mutant (B) embryos at the 1-somite stage; dorsal view. Note the reduced medial expression domain of pax[zf-b] (arrowhead). (C,D) Expression of pax[zf-b] at the midbrainhindbrain boundary (arrow) and pax6 (forebrain, eye anlage and hindbrain) in wild-type (C) and spg^m216 mutant (D) embryos at the 10-somites stage; dorsal view. (E,F) Lateral view of embryos in C and D, respectively. Note the absence of ventral pax[zf-b] expression at the midbrain-hindbrain boundary and the shift of the pax6 expression domains in forebrain and hindbrain with respect to each other (arrowhead). (G,H) Expression of wnt1 in wild-type (G) and spg^m216 mutant (H) embryos at the 14-somites stage. Note the reduction of wnt1 expression at the midbrain-hindbrain boundary (arrow). (I,J) Expression of pax[zf-b] (optic stalk, midbrainhindbrain boundary (arrow), hindbrain) in wild-type (G) and spg^m216 mutant (H) embryos at 26.5 hpf.